Sheet registration apparatus for printing machine

ABSTRACT

Apparatus is provided for use in a printing machine to insure proper registration of each sheet of printing stock with a printing roller assembly before the sheet is advanced through the assembly. The apparatus is mounted above the printing stock magazine and operates to displace the top sheet laterally against a guide after the sheet is separated from the underlying stack but before the sheet is engaged by a vacuum gripping assembly and advanced forwardly toward the printing roller assembly. The gripping assembly is actuated by a rocker shaft which extends transversely to the path of movement of the sheets, and the sheet registration apparatus is actuated by the rocker shaft so that it is synchronized with the motion of the gripping assembly. The registration apparatus includes a foot assembly which engages the upper surface of the top sheet and displaces the sheet laterally as a lever which mounts the foot assembly is pivoted upwardly by an actuator fixedly secured to the rocker shaft.

United States'Patent Wood [ Jan. 21, 1975 SHEET REGISTRATION APPARATUS FOR PRINTING MACHINE [76] Inventor: Vernon Wood, 167 Harvey Ave.,

Doylestown, Pa. 18901 [22] Filed: Oct. 23, 1973 [21] Appl. No.: 408,514

[56] References Cited UNITED STATES PATENTS 567,356 9/1896 Parker et al. 271/59 2,129,567 9/1938 Danielsson 271/59 2,195,545 4/1940 Stobb 271/5 2,553,148 5/1951 Rowlands 271/59 FOREIGN PATENTS OR APPLICATIONS 9,977 4/1916 Great Britain 271/59 Primary ExfiminerEvon C. Blunk Assistant Examiner-James W. Miller Attorney, Agent, or Firm-Howson & Howson [57] ABSTRACT Apparatus is provided for use in a printing machine to insure proper registration of each sheet of printing stock with a printing roller assembly before the sheet is advanced through the assembly. The apparatus is mounted above the printing stock magazine and operates-to displace the top sheet laterally against a guide after the sheet is separated from the underlying stack but before the sheet is engaged by a vacuum gripping assembly and advanced forwardly toward the printing roller assembly. The gripping assembly is actuated by a rocker shaft which extends transversely to the path of movement of the sheets, and the sheet registration apparatus is actuated by the rocker shaft so that it is synchronized with the motion of the gripping assembly. The registration apparatus includes a foot assembly which engages the upper surface of the top sheet and displaces the sheet laterally as a lever which mounts the foot assembly is pivoted upwardly by an actuator fixedly secured to the rocker shaft.

10 Claims, 5 Drawing Figures PATENTED JANE 1 I975 sum 2 OF 2 FIGS.

FIGA

FIGS.

SHEET REGISTRATION APPARATUS FOR 4 PRINTING MACHINE The present invention relates to sheet-feeding apparatus, and more particularly, the present invention relates to apparatus for effecting registration of sheets of printing stock in a printing machine.

The present invention is described in Disclosure Document Number 019,611, filed on May 31, 1973.

The conventional lithographic printing machine has a printing roller assembly which applies an inked image onto a sheet of printing stock as the sheet advances through the roller assembly after being separataed from a stack of printing stock contained in a magazine located ahead of the roller assembly. The magazine in a conventional printing machine has a lateral guide which engages the edges of the sheets in the stack to position the sheets properly with respect to the roller assembly. If the sheets are cut squarely and to precisely the same dimensions, and their edges are in alignment, the lateral guide ensures proper registry of each sheet with the printing roller assembly.

In the printing trade, it is customary for printers to cut sheets of printing stock to various dimensions to meet customers specifications prior to printing. It is difficult, however, for printers to cut the sheets precisely to the same dimensions and to align their edges properly in a stack before loading the stack into the magazine of the printing machine. If each sheet is advanced only once through themachine, the lack of perfect registration of each sheet with respect to the printing rollers would not be noticeable. However, there are certain situations in which it is desirablefor the sheets to be advanced through the printing machine a number of times. For instance, when printing multi-color images on the sheet, the sheet is advanced through the machine a number of times and a different color is imprinted each time. If the sheets are not in perfect registry with the printing rollers, the colors tend to overlap and the images tend to be blurred. As a result, this lack of perfect registration prevents certain types of printing machines from being utilized successfully to print multi-color images.

With the foregoing in mind, it is a primary object of the present invention to provide novel apparatus for use in a printing machine to ensure proper registration of printing stock with a printing roller assembly in the machine.

It is another object of the present invention to provide a simple and inexpensive mechanism which is capable of being installed rapidly with a minimum of tools on a printing machine to improve the printing quality of the machine.

It is a further object of the present invention to provide unique sheet feeding apparatus which operates in a printing machine to displace a sheet laterally against a guide after the sheet is separated from an underlying stack to register the sheet with printing rollers in the machine and to improve the feeding of sheets to the rollers.

As a further object, the present invention provides a bolt-on attachment for use with a certain type of printing machine to enable the machine to print high quality multi-color images.

More specifically, the present invention provides a mechanism which operates in conjunction with sheet feeding means in a printing machine to ensure registration of each sheet of printing stock before the sheet is advanced between printing rollers in the machine. The sheet is separated from a stack of sheets contained in a magazine and advanced forwardly by a vacuum gripping assembly which is actuated by a rocker shaft which overlies the magazine. The rocker shaft is connected by arms to the gripping assembly for displacing the gripping assembly vertically in opposite directions as the rocker shaft pivots in alternate directions. The sheet registration mechanism includes a foot assembly mounted on one end ofa lever which pivots about a fulcrum provided by a frame fastened to the side of the machine above the magazine. The lever displaces the foot assembly downwardly and laterally in timed relation with the motion of the gripping assembly with the timing being provided by a cam element which is fixedly secured to the rocker shaft to engage the other end of the lever for pivoting the same as the rocker shaft pivots. With this structure, the lateral edge of the top sheet of the stack is engaged against the-guide after the sheet is separated from the underlying stack bya'n air jet but before the sheet is gripped and advanced forwardly between the printing rollers.

These and other objects, features and advantages of the present invention should become apparent from the following description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front elevational view of sheet registration apparatus embodying the present invention, the view illustrating the apparatus mounted above a stack of printing stock contained in the magazine of a printing machine;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, the view illustrating in full lines the position of the vacuum gripping assembly in itsinactive position and illustrating in broken lines the positions of the vacuum-gripping assembly during feeding of a sheet leftward toward a printing roller assembly;

FIG. 3 is a sectional view taken along lines 3-3 in FIG. 2, the view illustrating in broken lines various alternate positions for a sheet-displacing foot assembly;

FIG. 4 is a greatly enlarged fragmentary view of a portion of the foot assembly illustrated in FIG. I, the view illustrating the foot assembly displacing a sheet rightward against a lateral guide; and

FIG. 5 is a perspective view of a modified foot assembly which may be employed satisfactorily in the apparatus of the present invention.

Referring now to the drawings, there is illustrated in FIG. 1 one type of conventional printing machine M for which the apparatus of the present invention is designed. The machine M has a magazine 10 which is adapted to contain a stack of sheets 11, ll of printing stock. The magazine 10 has a righthand lateral guide 12 which engages the righthand edges of the sheets 11, 11 in the stack, and the magazine 10 has a lefthand guide 13 which engages the lefthand edges of the sheets ll. The lefthand guide 13 mounts a leaf spring 14 along its upper margin for urging the uppermost ones of the sheets 11, 11 rightward toward the righthand guide 12. In the conventional printing machine, the lefthand guide 13 is mounted for movement toward and away from the left-hand edges of the sheets in order to permit the magazine 10 to accommodate sheets having various widthwise dimensions.

As best seen in FIG. 2, the magazine 10 has a forward stop 15 which extends between the guides 12 and 13 for engaging the front edges of the sheets 11, 11 in the stack. A series of fingers, such as the finger 16 in FIG. 2, extend rightward or rearwardly from the stop 15 to overlie the front margin of the top sheet 11a to limit upward movement thereof when the sheet 11a is separated from the underlying sheets. Separation is effected by an air jet which issues from a port 16a which is uncovered when the finger 16 moves upwardly during operation of the machine. The fingers 16, 16 are displaced vertically in unison by a conventional actuator which is not illustrated in order to simplify the drawmgs.

The top one 11a of the separated sheets is lifted upwardly beyond the fingers 16, 16 and advanced leftward toward printing rollers 18 and 19 by a vacuumgripping asembly 20. The gripping assembly 20 comprises a horizontally-disposed hollow tube 21 which extends parallel to the axis of rotation of the printing rollers l8 and 19 transverse to the path of movement of the sheet 11a. The tube 21 overlies the front of the magazine 10, and a series of suction cups 22, 22 are connected in spaced relation to the tube 21 by depending hollow stems 23, 23. A vacuum is created inside the tube 21 to cause the cups 22, 22 firmly to grip the top sheet 11a for lifting the same upwardly beyond the fingers 16, 16 and feeding the sheet 11a toward the printing rollers 18 and 19 when the cups 22, 22 are displaced upwardly and pivoted forwardly or clockwise as indicated in broken lines in FIG. 2,.

In order to displace the suction cups 22, 22 vertically, a pair of arms, such as the righthand arm 25, connects the tube 21 to a rocker shaft 24 which extends parallel to the tube 21 and which pivots alternately in opposite directions through a predetermined arc. The rocker shaft 24 thus displaces the arm 25, the tube 21 and the suction cups 22, 22 upwardly and downwardly in timed relation with the rotation of the printing rollers 18 and 19. The mechanisms which pivot the rocker shaft 24 and the tube 21 are located at the lefthand side of the machine M; however, such mechanisms are conventional and have been omitted from the drawings for the sake of simplicity.

During operation of the machine M, the printing cycle begins when the rocker shaft 24 pivots in a counterclockwise direction (FIG. 2) to displace the suction cups 22, 22 downwardly into engagement with the top sheet 11a for gripping the same. At the same time, the upper sheets 11, 11 in the stack are separated from the underlying sheets by air flowing from the ports 16a, 16a whichare uncovered as the fingers l6, 16 move upwardly. The top sheet 11a is gripped when the rocker shaft 24 reaches its clockwise limit position. The top sheet 11a is lifted upwardly beyond the fingers 16, 16 when the rocker shaft 24 pivots in the opposite or counterclockwise direction to its home position indicated in full lines in FIG. 2. The tube 21 is thereafter pivoted clockwise (FIG. 2) about its longitudinal axis to feed the front edge of the top sheet 110 between nip rollers 27 and 28 which advance the sheet 1 1a between the printing rollers 18 and 19.

The printing machine described thus far is manufac tured by the A. B. Dick Company as Models 350, 360, 380 and 385. Although the machine operates satisfactorily, there are occasions when all of the edges of the sheets 11, 11 in the stack are not aligned with one another and some are spaced from the righthand guide 12. For instance, this tends to occur when the sheets are cut manually or when the sheets are advanced through the machine M several times, such as when multicolor images are printed on the sheets. Because the edges of the sheets are not aligned with the guide 12, they do not register properly with respect to the printing rollers 18 and 19 so that imprinted multicolor images lack clarity, and the colors overlap one another. If the printing machine operator attempts to force the edges of the sheets against the righthand guide 12, as by moving the lefthand guide 13 rightward. the sheets 11, 11 tend to buckle longitudinally and the resulting lateral pressure on the sheets causes them to feed improperly, slowing printing production.

In accordance with the present invention, apparatus 30 is provided for ensuring proper registry of each sheet with the printing rollers in a printing machine to enable high quality multicolor images to be imprinted on the sheets. To this end, the apparatus 30 is designed to displace the top sheet 11a in the stack laterally against the righthand guide 12 after the sheet 11a is separated from the underlying sheets 11, 11 in the stack by the air jet but before the sheet 11a is gripped by the gripping assembly 20 and advanced forwardly toward the printing rollers 18 and 19. As best seen in FIG. 1, the apparatus 30 comprises a foot assembly 31 for operatively engaging the top sheet 11a and means for displacing the foot assembly 31 downwardly and laterally for sliding the sheet 11a rightward to butt its righthand edge against the righthand guide 12 in timed relation with the motion of the gripping assembly 20. In the illustrated embodiment, the foot displacing means includes a lever 32 which extends transversely to the normal path of movement of the sheets and which pivots about a horizontal fulcrum 33. The fulcrum is provided by a frame member 36 which is secured to the right side of the machine M and which extends leftward above the magazine 10. A pair of posts 36b, 36b project upwardly from the left end of the frame 36, and the posts 36b. 36b mount a bushing 38 which provides the fulcrum or pivot axis for the lever 32. The right end of the frame 36 has a downturned flange 36a which is secured to the machine by bolts 35, 35

The foot assembly 31 is located leftward or inboard of the fulcrum 33 so that when the lever 32 pivots in a counterclockwise direction (FIG. 1), the foot assembly 31 moves through an arc and engages the top sheet 11a to displace it laterally rightward against the guide 12. In the present invention, the lever 32 is pivoted in timed relation with respect to the gripping assembly 20, so that the sheet 11a is engaged with the guide 12 immediately prior to engagement of the forward margin of the sheet 11a by the suction cups 22, 22 of the gripping assembly 20. In the illustrated embodiment, motion of the lever 32 is synchronized with the motion of the rocker shaft 24, and hence the gripping assembly 20, by means of actuator assembly 40 which connects the rocker shaft 24 to the outboard end of the lever 32. As best seen in FIG. 2, the actuator assembly 40 includes a collar 41 which is mounted to the rocker shaft 24 through a protrusion 25a of the arm 25 and a cam element 42 which extends rearwardly from the underside of the collar 41 below the rocker shaft 24 to engage the underside of the lever 32 outboard of its pivot axis 33. The actuator assembly 40 is rendered angularly adjustable with respect to the shaft 24 during set-up by the bolt 43 which constricts the collar onto the protrusion 25a. With the structure, pivotal movement of the rocker shaft 24 in a counterclockwise direction (FIG. 2) displaces the arm 25 downwardly and the cam element 42 upwardly. The cam element 42 raises the outboard end of the lever 32 and pivots the inboard end of the lever 32 downwardly. The foot assembly 31, which depends from the inboard end of the lever 32, moves downwardly to engage the top sheet 11a for displacing its righthand edge laterally rightward against the righthand guide 12. The timing provided by this structure ensures engagement of the edge of the top sheet 1 1a with the guide 12 an instant before the rocker shaft 24 reaches its counterclockwise limit position and the suction cups 22, 22 engage the top sheet 11a. As a result, the edge of the top sheet 11a is properly aligned with respect to the guide 12 before the sheet is gripped and advanced between the nip rollers 27 and 28 for subsequent advancement between the printing rollers 18 and 19. Thus, proper registration of the sheet 11a with respect to the printing rollers 18 and 19 is ensured.

The foot assembly 31 is disengaged from the top sheet 11a after the top sheet 11a is gripped by the suction cups 22, 22. As best seen in FIG. 2, the gripping assembly 20 moves upwardly as the rocker shaft 24 pivots in the clockwise direction into its home position to cause the front margin of the top sheet 11a to move upwardly beyond the fingers 16, 16 prior to insertion of the sheet 11a between the nip rollers 27 and 28. In order to ensure disengagement of the foot assembly 31 from the top sheet 11a prior to forward movement of the top sheet, an extension spring 45 is connected between the righthand end of the lever 32 and the frame member 36. The spring 45 biases the righthand end of the lever 32 downwardly and maintains the same in engagement with the cam element 42, so that as the rocker shaft 24 pivots in the clockwise direction and the cam element 42 moves downwardly, the spring 45 pulls the righthand end of the lever 32 downwardly to raise the lefthand end of the lever 32 upwardly. This disengages the foot assembly 31 from the top sheet 1 1a and returns the foot assembly 31 to its home position to be ready for the next cycle.

In the conventional printing machine, the top sheet 11a is normally maintained at a predetermined level to ensure proper feeding. For this purpose, the level of the magazine is automatically adjusted in response to depletion of the stack 11. In machines of the above construction, this is effected by fingers which sense the level of the top sheet and which actuate a magazine lifting mechanism when the elevation of the top sheet drops below a preset level to maintain the top sheet within a predetermined range of the present level.

In order to enable the apparatus 30 of the present invention to operate properly without regard to normal variations in the level of the top sheet 11a in the stack, the foot assembly 31 is mounted to the inboard end of the lever 31 by a resilient connection which provides a certain amount of lost motion between the foot assembly 31 and the lever 32. To this end, the foot assembly 31 comprises a pad of friction material 50 and a leaf 51 of spring steel which mounts the pad 50. As best seen in FIG. 1, the leaf spring 51 is connected to the inboard end of the lever 32 by an arm 53 which extends leftward beyond the end of the lever 32. The leaf spring 51 is fastened to the left end of the arm 53 by a verticallydisposed bolt 52, and the leaf spring 51 extends rightward below the arm 55 in spaced relation at an acute angle therewith. The pad of friction material 50 is carried on the underside of the-leaf spring 51 adjacent its rightwardmost terminus which is located inboard of the lever fulcrum 33.

In this embodiment, the arm 53 is fabricated of spring steel, and both the arm 53 and the leafSl are resiliently deflectable in an upward direction in response to upward pressure on the pad 50. Thus, regardless of the level of the top sheet 11a, the pad 50 applies about the same pressure to the sheet lla whether the sheet 11a is at its uppermost or lowermost level within its range of levels. Moreover, it has been found that this structure tends to yield laterally leftward and upward when the righthand edge of the top sheet 11a engages the guide 12. As a result, the sheet 11a is prevented from buckling longitudinally after registration is effected. In the preferred foot assembly, the arm 53 and leaf 51 are approximately 3 inches long and about 1 inch wide. The arm 53 is approximately 0.005 inch thick, and the leaf5l is approximately 0.010 inch thick. Thus, the leaf 51 is stiffer than the arm 53 so that the arm 53 tends dto deflect upward relatively readily. This foot construction has been tested and found satisfactory when used in printing sheets having a basis weight of 20-l00 lbs/ream (24 inches X 36 inches 500 sheets).

The pad 50 is normally spaced a slight distance from the top sheet 11a when the lever 32 is in its home position as illustrated in FIG. 1. In order to regulate the spacing, the foot assembly 31 is mounted for vertical adjustment relative to the inboard end of the lever 32. For this purpose, the righthand end of the arm 53 mounts an upstanding threaded fastener 59, and an internally-threaded nut element 55 is mounted on the inboard end of the lever 32. The nut element 55 is interrupted, and the lever 32 has a recess 56 in registry with the interruption for receiving a lower locking knob 57. An upper locking knob 58 engages the upper end of the nut element 55, and both locking knobs 57 and 58 threadedly engage the threaded fastener 59. With this structure, the level of the arm-extension 53 may be raised or lowered simply by loosening the upper knob 58 and rotating the lower knob 57 in one direction or the other until the desired level is reached. It is noted that this structure permits the arm 53 to be pivoted about a vertical axis, and the bolt 52 which connects the leaf 51 to the arm 53 permits the leaf 51 to pivot about a vertical axis relative to the arm 53. As a result, the foot assembly 31 may be disposed in the position illustrated in broken lines in FIG. 3 to enable the apparatus 30 to be utilized satisfactorily in printing sheets of widths narrower than illustrated by permitting the position of the pad to be located as to engage the sheet at about its widthwise median, or outboard thereof.

In setting up the apparatus 30, the flange 36a of the frame 36 is bolted to pre-existing holes in the side of the machine M. The lever 32 is disposed horizontally, and the cam element 42 engaged with the outboard end of the lever 32 when the gripping assembly 20 is in its home or inactive position with the suction cups 22, 22 spaced from the top sheet is illustrated in FIG. 2. The bolt 43 is then tightened to secure the cam element 42 to the rocker shaft 24. With the lever 32 disposed horizontally, the level of the arm-extension 53, and hence the level of the pad 50, is adjusted so that the pad 50 is spaced from the surface of the top sheet 11a when the top sheet 11a is in its uppermost level. This should ensure that the righthand edge of the sheet 11a is engaged with the guide 12 when the lever 32 pivots in alternate directions as the rocker shaft 24 pivots, so that the motion of the foot assembly 31 is synchronized with the motion of the gripping assembly to ensure proper positioning of the top sheet 11a before it is gripped and advanced between the printing rollers 18 and 19.

In the illustrated embodiment, both the arm extension 53 and the leaf spring 51 are of spring steel and are resiliently deflectable in an upward direction relative to the inboard end of the lever 32. This construction has been tested and found satisfactory for most mediumweight papers as noted above; however, it has been found desirable, when the apparatus 30 is utilized in printing sheets having higher basis weights, i.e., above 100 lbs/ream, to make the arm-extension 53 rigid to prevent it from deflecting upwardly. This structure is illustrated in FIG. 5, and is dimensionally similar to the foot assembly of FIGS. 1-3. This foot structure has been tested and found to provide the desired sheetdisplacement action for a heavy sheet which is suffrciently inflexible as to resist buckling longitudinally even when strong lateral forces are applied to the upper surface thereof.

The pad 50 is preferably provided by a mass of sponge rubber material which is somewhat elastic in shear, i.e., which permits the leaf spring 51 to move rightward relative to the top sheet lla after the edge of the sheet 11a engages the guide 12, such as illustrated schematically in FIG. 4. This resilient shear action, as well as the upward deflections of the leaf spring 51 and arm 53, is believed to minimize the tendency of the top sheet 11a to buckle longitudinally as the lever 32 continues to pivot after the edge of the top sheet 11a engages the guide 12. In the present instance, the pad 50 is about one fourth inch thick and extends the full width of the leaf spring 51; however, if additional gripping action is desired, the pad 50 may extend laterally of the leaf spring 51.

In order to ensure against longitudinal buckling of the sheet 11a due to the lateral pressure applied by the pad 50, a front hold-down bar 60 is provided. As best seen in FIG. 3, the hold-down bar 60 extends along the front margin of the top sheet 11a and the bar 60 is pivotally connected to the machine M by arms such as the right arm 60a. The weight of the bar 60 on the sheet keeps the front margin of the sheet 11a from being blown about when air is forced between the sheets to separate the same and prevents longitudinal buckling of the sheet lla as the pad 50 moves laterally to register the sheet 11a.

It has also been found desirable to employ a rear hold-down bar 62 to perform a similar function as the front bar 60 but with respect to the rear margin of the top sheet 11a. As best seen in FIG. 3, the rear bar 62 is suspended from a transverse rod 63 on the machine frame. The bar 62 extends transversely to the part of movement of the sheet 11a and engages the rear margin of the top sheet 110 to weigh down the same. Although the apparatus operates satisfactorily without the bars, it has been found desirable to utilize the bars when printing relatively lightweight sheets.

The apparatus of the present invention is designed to be used in conjunction with certain models of printing machines produced by one manufacturer; however, it should be apparent that with certain modifications, the apparatus may be utilized satisfactorily in conjunction with other types of printing machines having generally similar sheet advancement mechanisms. It has been found that apparatus also operates to improve the feeding of sheets of printing stock since proper feeding is effected even when the stock is spaced from the left and righthand guides in the magazine. The lack of lateral pressure on the side edges of the sheets enables the top sheet to be separated from the stock and fed freely, thereby minimizing downtime of the machine due to sheet jamups, etc. Thus, printing production is significantly improved.

While a preferred embodiment of the present invention has been described in detail, various modifications, alterations and changes may be made without departing from the spirit and scope of the present invention as defined in the appended claims.

It is claimed:

1. In a machine having printing means, magazine means for containing a stack of sheets of printing stock adjacent said printing means, gripping means for engaging the uppermost one of said sheets and advancing said one sheet in a predetermined path toward said printing means, means for operating said gripping means including a rocker shaft disposed transversely to the path of movement of said sheet and pivotable in alternate directions between limit positions, and guide means disposed alongside said magazine outboard of said path of movement for positioning said stack in said magazine, the improvement comprising: apparatus for effecting proper registry of said one sheet relative to said printing means, including foot means overlying said magazine means and adapted to engage a top one of said sheets in said stack; means for displacing said foot means downwardly from an inactive position overlying said one sheet to an active position engaged with said sheet and for displacing said sheet transversely to said path of movement when said foot means is in said active position; and means for synchronizing movement of said foot displacing means with movement of said sheet gripping means to ensure displacement of said sheet transversely against said guide means before said sheet is engaged by said gripping means; said foot displacing means including a lever, frame means mounting said lever to said machine to pivot about an axis extending in the direction of movement of said one sheet, and means carried at one end of said lever inboard of said axis for mounting said foot means to said lever; and said synchronizing means including actuator means engaging the other end of said lever outboard of said axis and means fastening said actuator means to said rocker shaft for causing said one end of said lever to pivot downwardly in response to pivotal movement of said rocker shaft in one direction; whereby the foot means is displaced downwardly and laterally in timed relation with movement of the gripping means.

2. Apparatus according to claim 1 including return means coupling said lever to said actuator means for causing said inboard end of said lever to move upwardly in response to pivotal movement of said rocker shaft in a direction opposite said one direction, whereby the foot means disengages the top sheet after the sheet is displaced laterally against the guide means.

3. Apparatus according to claim 2 wherein said return means includes a spring connecting said lever to said frame means for biasing said outboard end of said lever downwardly.

4. Apparatus according to claim 3 wherein said actuator means includes a cam element disposed transversely to the pivot axis of said rocker shaft, a collar connected to said cam element, and means adjustably securing said collar to said rocker shaft to afford adjustment of said cam element angularly with respect to said rocker shaft.

5. In a machine having printing means, magazine means for containing a stack of sheets of printing stock adjacent said printing means, gripping means for engaging the uppermost one of said sheets and advancing said one sheet in a predetermined path toward said printing means, means for operating said gripping means including a rocker shaft disposed transversely to the path of movement of said sheet and pivotable in. alternate directions between limit positions, and guide means disposed alongside said magazine outboard of said path of movement for positioning said stack in said magazine, the improvement comprising: apparatus for effecting proper registry of said one sheet relative to said printing means, including foot means overlying said magazine means and adapted to engage a top one of said sheets in said stack; means for displacing said foot means downwardly from an inactive position overlying said one sheet to an active position engaged with said sheet and for displacing said sheet transversely to said path of movement when said foot means is in said active position; and means for synchronizing movement of said foot displacing means with movement of said sheet gripping means to ensure displacement of said sheet transversely against said guide means before said sheet is engaged by said gripping means; said foot means including a pad of friction material; and said mounting means including at least one resilient element connecting said pad to said one end of said lever to afford vertical resilient deflection of said pad relative to said one end of said lever, said resilient element including an inclined leaf spring mounting said pad at its lower end and an arm connected at one end to the upper end of said leaf spring and connected at its other end to one end of said lever.

6. Apparatus according to claim 5 wherein said arm is rigid relative to said leaf spring so that said leaf spring is capable of deflecting upwardly relative to said arm.

7. Apparatus according to claim 5 wherein said arm is fabricated of spring material and is vertically deflectable relative to said one end of said lever.

8. Apparatus according to claim 7 wherein said leaf spring is stiffer than said arm.

9. Apparatus according to claim 5 including means connecting said other end of said arm to said one end of said lever to afford vertical adjustment and pivotal movement of said arm about an upright axis relative to said lever and means mounting said upper end of said leaf spring to pivot about an upright axis relative to said arm, whereby the position of the foot may be adjusted in a horizontal plane relative to the top sheet.

10. Apparatus according to claim 9 wherein said connecting means includes an upstanding externallythreaded stem fixedly secured to said other end of said arm and a similarly disposed internally-threaded nut element carried by the inboard end of said lever and threadedly engaging said stem, said nut element being interrupted intermediate its length and said lever having a recess in registry with the interruption, a pair of locking knobs threadedly engaging said stem, one of said knobs being located in said interruption and recess and the other of said knobs engaging one end of said nut element, whereby the level of the pad may be adjusted upon rotation of the one knob. 

1. In a machine having printing means, magazine means for containing a stack of sheets of printing stock adjacent said printing means, gripping means for engaging the uppermost one of said sheets and advancing said one sheet in a predetermined path toward said printing means, means for operating said gripping means including a rocker shaft disposed transversely to the path of movement of said sheet and pivotable in alternate directions between limit positions, and guide means disposed alongside said magazine outboard of said path of movement for positioning said stack in said magazine, the iMprovement comprising: apparatus for effecting proper registry of said one sheet relative to said printing means, including foot means overlying said magazine means and adapted to engage a top one of said sheets in said stack; means for displacing said foot means downwardly from an inactive position overlying said one sheet to an active position engaged with said sheet and for displacing said sheet transversely to said path of movement when said foot means is in said active position; and means for synchronizing movement of said foot displacing means with movement of said sheet gripping means to ensure displacement of said sheet transversely against said guide means before said sheet is engaged by said gripping means; said foot displacing means including a lever, frame means mounting said lever to said machine to pivot about an axis extending in the direction of movement of said one sheet, and means carried at one end of said lever inboard of said axis for mounting said foot means to said lever; and said synchronizing means including actuator means engaging the other end of said lever outboard of said axis and means fastening said actuator means to said rocker shaft for causing said one end of said lever to pivot downwardly in response to pivotal movement of said rocker shaft in one direction; whereby the foot means is displaced downwardly and laterally in timed relation with movement of the gripping means.
 2. Apparatus according to claim 1 including return means coupling said lever to said actuator means for causing said inboard end of said lever to move upwardly in response to pivotal movement of said rocker shaft in a direction opposite said one direction, whereby the foot means disengages the top sheet after the sheet is displaced laterally against the guide means.
 3. Apparatus according to claim 2 wherein said return means includes a spring connecting said lever to said frame means for biasing said outboard end of said lever downwardly.
 4. Apparatus according to claim 3 wherein said actuator means includes a cam element disposed transversely to the pivot axis of said rocker shaft, a collar connected to said cam element, and means adjustably securing said collar to said rocker shaft to afford adjustment of said cam element angularly with respect to said rocker shaft.
 5. In a machine having printing means, magazine means for containing a stack of sheets of printing stock adjacent said printing means, gripping means for engaging the uppermost one of said sheets and advancing said one sheet in a predetermined path toward said printing means, means for operating said gripping means including a rocker shaft disposed transversely to the path of movement of said sheet and pivotable in alternate directions between limit positions, and guide means disposed alongside said magazine outboard of said path of movement for positioning said stack in said magazine, the improvement comprising: apparatus for effecting proper registry of said one sheet relative to said printing means, including foot means overlying said magazine means and adapted to engage a top one of said sheets in said stack; means for displacing said foot means downwardly from an inactive position overlying said one sheet to an active position engaged with said sheet and for displacing said sheet transversely to said path of movement when said foot means is in said active position; and means for synchronizing movement of said foot displacing means with movement of said sheet gripping means to ensure displacement of said sheet transversely against said guide means before said sheet is engaged by said gripping means; said foot means including a pad of friction material; and said mounting means including at least one resilient element connecting said pad to said one end of said lever to afford vertical resilient deflection of said pad relative to said one end of said lever, said resilient element including an inclined leaf spring mounting said pad at its lower end and an arm connected at one end to the uPper end of said leaf spring and connected at its other end to one end of said lever.
 6. Apparatus according to claim 5 wherein said arm is rigid relative to said leaf spring so that said leaf spring is capable of deflecting upwardly relative to said arm.
 7. Apparatus according to claim 5 wherein said arm is fabricated of spring material and is vertically deflectable relative to said one end of said lever.
 8. Apparatus according to claim 7 wherein said leaf spring is stiffer than said arm.
 9. Apparatus according to claim 5 including means connecting said other end of said arm to said one end of said lever to afford vertical adjustment and pivotal movement of said arm about an upright axis relative to said lever and means mounting said upper end of said leaf spring to pivot about an upright axis relative to said arm, whereby the position of the foot may be adjusted in a horizontal plane relative to the top sheet.
 10. Apparatus according to claim 9 wherein said connecting means includes an upstanding externally-threaded stem fixedly secured to said other end of said arm and a similarly disposed internally-threaded nut element carried by the inboard end of said lever and threadedly engaging said stem, said nut element being interrupted intermediate its length and said lever having a recess in registry with the interruption, a pair of locking knobs threadedly engaging said stem, one of said knobs being located in said interruption and recess and the other of said knobs engaging one end of said nut element, whereby the level of the pad may be adjusted upon rotation of the one knob. 